The Xiris Blog

April was an extremely successful month for Xiris Automation! Read below for a recap of the month's events.

Tube Dusseldorf 2018

Xiris exhibited at Tube Dusseldorf 2018 in Dusseldorf, Germany, from April 16-20. This was an important opportunity for those in the tube and tube processing industry to witness new technology and innovation in the field. We were thrilled to be an exhibitor at such a pre-eminent event!

Our team demonstrated how our innovative quality control solutions add value to tube and pipe welding activities, especially for detecting problems sooner in the tube manufacturing process using our WI2000 inspection system.Overall, it was an extremely successful event for Xiris and an excellent opportunity to engage with leaders in the tube processing and fabrication industries.

Rapid + TCT

Xiris exhibited at the Rapid + TCT conference in Forth Worth, Texas, USA from April 24-26. Rapid is a significant event for innovation in the additive manufacturing industry, and attracted leaders in 3D Manufacturing from around the world.

Through demonstrations and interactions with these companies, the Xiris team showed how our HDR weld cameras can decrease building times, reduce operating and engineering costs, and lower materials costs in research and development for Metal Additive Manufacturing. When our High Dynamic Range (HDR) weld cameras are added into an Additive Manufacturing machine, operators can monitor every step of the welding process in real time to ensure quality outputs, detecting any material placement issues such as warping without having to stop the machine.

Japan International Welding Show

Xiris attended the 2018 Japan International Welding Show in Tokyo from April 25- 28, displaying our cameras in the Matsumoto Group booth. This was Japan's largest exhibition of welding technology, and was thus an extremely significant opportunity for Xiris.

Our extremely durable, industrialized weld camera was on display at the show, as seen below.

If you are interested in learning about or displaying one of our cameras, please contact ushere.

Statistical Process Control (SPC) is the use of inspection data to determine the characteristics of a process, using techniques to find and remove abnormal variations in completed tubes. Variable data is quantitative and is generated from actual measurements, such as the Mismatch, Bead Height, Deflection or similar measurements obtained from the Xiris WI2000 Weld Inspection system when it is placed right after the weld box on a tube mill.

Variation is the difference between things that should be alike because they were produced under the same conditions. Variation can be measured and groups of these measurements can be plotted as a frequency distribution, or histogram. Since quality is a measure of conformance to specifications, poor quality results when variation falls outside the upper and lower specification limits.

SPC data can now be recorded and reviewed off line using the WI2000 measuring a number of parameters, including:

Mean - the average of a group of values of a particular measurement.

Median - the middle value of a group of ordered measurements.

Mode - the measurement occurring with the highest frequency. This is the peak of the histogram. In a true normal distribution, the mean, median and mode are all equal.

Range - the highest minus the lowest value in a set of measurement data. This is a simple measure of the dispersion, or spread, in a set of data.

Standard Deviation- a measure of dispersion computed from the square root of the sum of the deviations from the mean, divided by the total frequency.

Statistical process control uses the concept of subgroup sampling. This is a method of data collection that considers a series of consecutive measurements together as a single group. A typical subgroup size is five (5) measurements. In order to smooth out the variability associated with an individual measurement, five consecutive measurements would be considered together as a representative sample.

Following sub arc welding on the inside and outside of a helically welded pipe, the pipe must undergo inspection to be prepared for further processing or service in the field. This preparation step includes rigorous inspection and testing procedures, repair of defects, and application of anti-corrosion coatings before the pipe enters service.

Post-weld Scarfing in helical sub arc welding

Traditionally, post-weld inspection is done manually by an operator who walks around the exterior of the pipe or crawls through it as part of an offline process. The operator is responsible for identifying any weld undercut, incorrect weld wetting angles, or insufficient or excessive weld bead material from the process. It is not only time consuming, but it relies on the operator to be consistent to be able to catch all defects in the product.

A better solution is to use automatic inspection equipment such as the XirisWI3000 weld inspectionsystem, which can profile the entire weld bead after the flux has been removed or fallen away to detect problems sooner in the process. Usually used as an inline inspection tool post-weld, the WI3000 can also be used to provide the operator with feedback to make corrections reducing additional defects while marking the location of a defect to expedite the repair process.

Laser Bead Profile of a Weld Bead with a Too Steep Slope on the Right Side of the Bead

Information from the laser sensor is transmitted to a single image-processing system, allowing the operator to identify and control the welding parameters. The end result is a better, more objective measurement of the weld bead inspection process in advance of use of the pipe in the field.

Xiris Automation offers a full suite of products for your helical sub arc welding (HSAW) process. From the control and quality assurance of the initial forming and tacking stage by the XVC-1000, through the remote monitoring of process parameters during full-seam sub arc welding by the XVC-S, and the post-welding and post-scarfing inspection by the WI-3000, Xiris provides operators with the tools they need to prepare the highest-quality products they can.

To learn more about how Xiris Automation’s full suite of turnkey solutions can improve the quality and yield of your HSAW manufacturing process, contact one of our technical specialists today.

One-step Helical (or Spiral) Submerged Arc Welding (HSAW) processes do not use GMAW/GTAW systems to tack the material into pipe form like two- step processes, but rather perform full inner welds using a sub arc welder during the initial forming stage.

This one-step process is advantageous in that it requires less equipment, and therefore less shop floor space, but it results in significantly lower processing speeds compared to the two-step process.

Both one- and two-step HSAW processes use dual-system submerged arc welding with flux recovery systems to perform the complete welds, with a preliminary weld on the inner diameter and a secondary weld on the outer diameter. Using two HSAW systems in parallel allows the weld penetration depths to meet, providing a strong weld in wall thicknesses as large as 1”.

Cross section of Dual Sub Arc Welded Seam [1]

The quality of these welds is paramount to the success of the pipe. With applications in the transportation of oil, natural gas, water, and other flammable and nonflammable liquids, a small defect in the weld seam affects not only the density of the weld—causing higher risk of leaks—but also becomes a major point of corrosion-induced wear. Porosity, thermal cracking, undercut, and insufficient penetration are all critical defects caused by relatively common circumstances during the submerged arc welding process.

Detecting Defects Sooner With HDR Weld CamerasVarious standards organizations such as the American Society of Testing and Materials or the American Water Works Association prescribe hydrostatic testing to 2800 psi / 193 bar, as well as ultrasonic or radiography testing, to ensure the quality of the weld seam for its service life. But these tests determine the quality of the seam in a retroactive way, after the defects have already propagated throughout the tube.

The Xiris Weld Camera for Sub Arc applications, the XVC-S, is an affordable turnkey solution for monitoring the sub arc welding process. The XVC-S features an out-of-the box solution with integrated lighting, graphical-overlay-producing crosshairs, and a rugged housing suitable for the welding environment.

With on-screen monitoring tools, operators can easily identify and correct any deviations from standard operating procedures, including insufficient flux supply, misalignment of the torch or seam, and damage to the weld tip. The remote viewing monitor can display multiple processes, allowing a single operator to monitor the quality of the inner and outer sub arc welding processes simultaneously.

Operator remotely monitoring a sub arc welding process

The small size of the XVC-S camera allows it to be easily integrated into an existing sub arc welding mount and the high-voltage and high-temperature resistant design, combined with the built-in solid-state lighting, allows high-quality images to be produced even in the harshest environments. By ensuring the quality of the weld during the sub arc welding process itself, defects can be caught sooner and corrected before the quality of the entire pipe length is compromised—saving time, money, and resources to provide an overall more-efficient process.

By enabling greater visibility and control during processing and tacking, high dynamic range (HDR) weld cameras are a powerful tool to counter this risk.

The Advantages of HSAW

HSAW has a unique capability for producing large diameter pipes for flammable and nonflammable liquid transportation. While longitudinal pipe welding is limited to approximately 42” (1.1 m) outer diameter due to the size of the feedstock sheet, helical pipe welding is only limited by the size of the equipment, allowing pipes as large as 140” (3.6 m) outer diameter to be manufactured.

Helically welded pipe also has a distinct advantage over longitudinally welded pipe because the radial stress in the weld seam is not concentrated along a single axis but instead rotates around the circumference of the pipe, creating a more-even stress distribution. This advantage allows for thinner tube wall construction using more economical, non-high-strength materials.

Limiting Defects with HDR Weld Cameras

Spiral welded pipe is made using either one-stage or two-stage weld processing. While both processes begin with the incoming skelp coil of material being unwound, flattened, trimmed, squared, and then fed into the forming stage, in one-stage processing, the forming process is immediately followed by simultaneous inside and outside Submerged Arc Welding.

In two-stage processing, the material is formed and tack welded into the pipe body shape by a gas metal welder prior to the Submerged Arc Welding process. The tack welding stage is critical for the quality of the pipe because misalignment of the initial tack will cause defects when further processed during the Submerged Arc Welding stage. Numerous factors can cause misalignment, including defects in the metallurgical properties of the feedstock, gaps between sheets, misalignment of the welding heads, or dull tooling during the processing of the skelp coil.

With the latest in camera and software technology, the Xiris XVC-1000e high-dynamic-range weld camera permits the operator to see the spiral pipe feedstock, the weld head, and torch location relative to the weld seam during the welding process. By monitoring the images directly, an operator can make adjustments to the material inputs or torch position to quickly correct the fault before the defect propagates throughout the length of the weld. The camera’s robust, IP65-rated enclosure allows it to survive the harsh environments of HSAW pipe mills.

Additionally, the XVC-1000e can be used with Xiris’ seam tracking software, as shown in the figure below. The seam tracker software identifies the location of the welding head and the arc contact with the material and the material seam, detecting fluctuations in alignment. With such software, out-of-alignment conditions can automatically alert the operator to make process-control adjustments or even provide closed-loop feedback to automatically move the torch back into position.

Summary

Adding a Xiris XVC-1000e weld camera to an HSAW pipe mill can help operators monitor the feedstock material forming process and alignment to the welding torch, ensuring that minimal defects occur during the preliminary material processing and forming stages. In so doing, pipe weld quality can be improved, reducing the risk that weld defects will propagate down the pipe mill and make it to the customer.

Fuel line tubing is typically manufactured on an ERW welding mill similar to traditional seam welded tubing. Once the tube has been welded, it moves down the mill for further in-line processing that may include reducing, sizing, annealing and coating processes to meet the customer’s needs.

Fuel line tubing must be perfectly round in order to create a good seal when compression fittings are applied to it. The tube surface must be free from longitudinal scratches, grooves or beads in order to prevent a leak path from developing at the interface point of the fittings.

Immediately after the fuel line tube has been welded and before any further in-line processing is done, the weld bead must be scarfed (the process whereby the weld bead is cut off with a knife). Unfortunately, the scarfing process can be the primary contributor to creating a leak path on a compression fitting because:

1. Insufficient scarfing can leave a small portion of the weld bead protruding from the surface of the tube. This may be on either one or both sides of the weld bead where scarfing tool positioning is critical.

Insufficient Scarfing

2. Excessive scarfing may look perfectly round to the human eye however a non-uniform wall thickness may be lurking below the surface. What is not always apparent and usually only observed during thorough end cut inspection is a thinned portion of the tubing wall that may compromise the integrity of the tube. The reducing process applies enough external force to the tube that the tube may buckle or collapse, causing a deep surface groove.

Excessive Scarfing

3. A mismatched setup may also be a contributor to a non-uniform wall thickness. The scarfing tool may cut the bead on the outside diameter so that it looks perfectly round to the human eye, disguising the compromised wall thickness below the surface. Sufficient mismatch conditions will most certainly cause the tube to split on end forming later in the fabrication process.

Mismatched Defect, Post Scarfing

The Xiris WI2000/3000 Weld Inspection System uses laser-based imaging techniques to continually monitor the scarf zone for any variations in the scarf height, seam mismatch and possible scarf tool wear or chips that may cause a longitudinal line on the tube. By detecting and responding to these conditions proactively, a mill operator is able to reduce the chance of a leak path on the tube and avoid an unplanned stoppage to the mill due to a tube collapse during the reducing process.

For more information on how a Xiris Weld Inspection System can enhance your scarfing processes visitXiris.com